1. Field of the Invention
The present invention relates to dispensing all forms of media and, more particularly, to the efficient and accurate dispensing of fluid media in wafer processing applications.
2. Description of the Related Art
In the semiconductor chip fabrication process, it is well-known that there is a need to dispense different types of media such as liquid, semi-solid, and sometimes solid substances in various operations. For example, semiconductor wafer fabrication, polishing, and cleaning operations require precise and controlled amounts of media to be applied to a wafer. Examples of such operations include chemical mechanical polishing (CMP) and wafer cleaning. In CMP, a wafer is placed in a holder which pushes a wafer surface against a circulating belt pad or rotary pad table. The circulating belt pad as well as the rotary pad table uses a slurry which consists of chemicals and abrasive materials which facilitate the polishing. Therefore, a mechanism is typically used to dispense slurry onto the pad to effectuate polishing of the wafer.
Once wafers are polished, the wafers are processed through cleaning operations. Media is then dispensed from one or more media delivery mechanisms of a cleaning system to clean the wafer of contaminants accumulated during fabrication and polishing operations. In one example, in a cleaning operation, there is a desire to have a particular chemical such as HF, DI water, ammonia, and the like applied very precisely to a wafer to enact a particular cleaning operation. Therefore, there is a desire in the high technology field for a precise device to deliver media in very specific quantities. To do this, a complex combination of factors may need to be precisely controlled.
Unfortunately delivery systems used in wafer processing operations such as CMP and wafer cleaning tend to use various apparatuses such as valves in addition to various regulators and controls to deliver the desired amount of media onto the wafer or wafer cleaning station (e.g., such as to a brush). Such mechanisms are utilized in an attempt to achieve a particular flow rate, flow amounts, or a particular fluid pressure. Once these mechanisms are put into place, these systems will require detailed calibrations by skilled professionals to make them work as intended for a particular process. Such calibrations include adjusting the timing sequence of media application, the pressure of the fluid flow, the use of shut off valves, the regulating of fluid flow, the adjusting of diameters of flow tubes, and the like. These factors may be highly critical to making the processing conditions optimal for wafer production and processing.
Because these adjustments and calibrations are detailed, problems may arise if such calibrations are not done properly. Even if the calibrations and adjustments are done satisfactorily at the initial setup, over time the system will have to continually be maintained to ensure that the desired performance is maintained to ensure consistency in wafer cleaning from wafer lot to wafer lot. As can be appreciated, the time taken for such detailed setup and continual adjustments can be prohibitive for efficient or high throughput wafer production that demands consistency and repeatability over long term production cycles.
In addition, factors such as controlled application time spans and start and stop cycles must be carefully regulated during use in order to dispense the right amount of media. As can be seen, numerous complex combination of factors may need to be optimized for the proper application of media to a wafer in, for example, a wafer fabrication processes. Most importantly, a variation of a single factor may change flow rates dramatically, and many times necessitates that highly skilled personnel spend an excessive amount of time fine-tuning prior art media dispensing devices. As a result, there is a desire to have less complex but precise systems that enable the application of different types of media, and in particular for use in the wafer processing industry.
Therefore, there is a need for a method and an apparatus that overcomes the problems of the prior art by enabling easily configurable, adjustable, and highly accurate media dispensing.
Broadly speaking, the present invention fills these needs by providing a method and apparatus for efficiently and accurately dispensing media in a variety of different applications. It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, a device or a method. Several inventive embodiments of the present invention are described below.
In one embodiment, an apparatus for dispensing media is provided. The apparatus has a rotating element having a cylindrical bore with a first end and a second end where the rotating element rotates the first end and the second end. The apparatus also includes a housing which has a fixed input port and a fixed output port where the housing encloses the rotating element. In this embodiment, the first end and the second end of the rotating element intermittently switches between being aligned with the fixed input port and the fixed output port and being aligned with the fixed output port and the fixed input port, respectively. The apparatus also has a cylindrical piston contained within the cylindrical bore where the cylindrical piston has a length that is less than the cylindrical bore and switches from being closer to the fixed input port and the fixed output port.
In another embodiment, a method for dispensing media is provided. The method receives a first fixed quantity of media at an input. Then the first fixed quantity of media is rotated to an output. Thereafter, a second fixed quantity of media is received at the input and substantially simultaneously the first fixed quantity of media at the output is dispensed.
In yet another embodiment, a fluid dispenser to be used in wafer processing operations is provided. The fluid dispenser includes a rotating element which has a cylindrical bore with a first end and a second end where the rotating element rotates the first end and the second end. The fluid dispenser also includes a housing which has a fixed input port and a fixed output port where the housing encloses the rotating element. The first end and the second end of the rotating element intermittently switches between being aligned with the fixed input port and the fixed output port and being aligned with the fixed output port and the fixed input port, respectively. The fluid dispenser also has a cylindrical piston contained within the cylindrical bore where the cylindrical piston has a length that is less than the cylindrical bore and switches from being closer to the fixed input port and the fixed output port. In this embodiment, the cylindrical bore of the fluid dispenser receives a fluid from the fixed input port as the cylindrical piston moves toward the fixed output port and simultaneously dispenses the fluid from the fixed output port.
The advantages of the present invention are numerous. Most notably, by creating an apparatus and method to efficiently and accurately dispense media, wafer processing operations such as, for example, CMP and wafer cleaning processes may be conducted without concerns about over-application or under-application of media. Compared to the prior art, the present invention is a reliable and accurate dispensing device which has only three principal components. Therefore, the present invention is less complicated than generally available commercial dispensing devices. In addition, the present invention may be actuated by any variety of motivating devices which affects and controls rotary motion. This makes the present invention highly flexible to use. The present invention also has the advantage of using line pressure as a principal means of actuating the dispensing motion. This again assists in the enablement of consistent and accurate media application.
Furthermore, the volume of media dispensed can also be changed easily while exact repeatable volumes may be dispensed with each dispensing cycle. In addition to the accurate delivery of media, the present invention may also vary the cyclic dispensing rate. Therefore, the present invention has numerous features which enable accurate and dependable dispensing of media.
Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the present invention.